Expression of two Arabidopsis (Arabidopsis thaliana) apyrase (nucleoside triphosphate-diphosphohydrolase) genes with high similarity, APY1 and APY2, was analyzed during seedling development and under different light treatments using b-glucuronidase fusion constructs with the promoters of both genes. As evaluated by b-glucuronidase staining and independently confirmed by other methods, the highest expression of both apyrases was in rapidly growing tissues and/or tissues that accumulate high auxin levels. Red-light treatment of etiolated seedlings suppressed the protein and message level of both apyrases at least as rapidly as it inhibited hypocotyl growth. Adult apy1 and apy2 single mutants had near-normal growth, but apy1apy2 doubleknockout plants were dwarf, due primarily to reduced cell elongation. Pollen tubes and etiolated hypocotyls overexpressing an apyrase had faster growth rates than wild-type plants. Growing pollen tubes released ATP into the growth medium and suppression of apyrase activity by antiapyrase antibodies or by inhibitors simultaneously increased medium ATP levels and inhibited pollen tube growth. These results imply that APY1 and APY2, like their homologs in animals, act to reduce the concentration of extracellular nucleotides, and that this function is important for the regulation of growth in Arabidopsis.

Reverse Transcription - quantitative Polymerase Chain Reaction (RT-qPCR) is a standard technique in most laboratories. The selection of reference genes is essential for data normalization and the selection of suitable reference genes remains critical. Our aim was to 1) review the literature since implementation of the MIQE guidelines in order to identify the degree of acceptance; 2) compare various algorithms in their expression stability; 3) identify a set of suitable and most reliable reference genes for a variety of human cancer cell lines. A PubMed database review was performed and publications since 2009 were selected. Twelve putative reference genes were profiled in normal and various cancer cell lines (n = 25) using 2-step RT-qPCR. Investigated reference genes were ranked according to their expression stability by five algorithms (geNorm, Normfinder, BestKeeper, comparative ΔCt, and RefFinder). Our review revealed 37 publications, with two thirds patient samples and one third cell lines. qPCR efficiency was given in 68.4% of all publications, but only 28.9% of all studies provided RNA/cDNA amount and standard curves. GeNorm and Normfinder algorithms were used in 60.5% in combination. In our selection of 25 cancer cell lines, we identified HSPCB, RRN18S, and RPS13 as the most stable expressed reference genes. In the subset of ovarian cancer cell lines, the reference genes were PPIA, RPS13 and SDHA, clearly demonstrating the necessity to select genes depending on the research focus. Moreover, a cohort of at least three suitable reference genes needs to be established in advance to the experiments, according to the guidelines. For establishing a set of reference genes for gene normalization we recommend the use of ideally three reference genes selected by at least three stability algorithms. The unfortunate lack of compliance to the MIQE guidelines reflects that these need to be further established in the research community.

Epithelial ovarian cancer is the fifth most common cause of cancer in women worldwide bearing the highest mortality rate among all gynecological cancers. Cell membrane glycans mediate various cellular processes such as cell signaling and become altered during carcinogenesis. The extent to which glycosylation changes are influenced by aberrant regulation of gene expression is nearly unknown for ovarian cancer and remains crucial in understanding the development and progression of this disease. To address this effect, we analyzed the membrane glycosylation of non-cancerous ovarian surface epithelial (HOSE 6.3 and HOSE 17.1) and serous ovarian cancer cell lines (SKOV 3, IGROV1, A2780, and OVCAR 3), the most common histotype among epithelial ovarian cancers. Nglycans were released from membrane glycoproteins by PNGase F and analyzed using nano-liquid chromatography on porous graphitized carbon and negative-ion electrospray ionization mass spectrometry (ESI-MS). Glycan structures were characterized based on their molecular masses and tandem MS fragmentation patterns. We identified characteristic glycan features that were unique to the ovarian cancer membrane proteins, namely the "bisecting N-acetyl-glucosamine" type N-glycans, increased levels of ␣ 2-6 sialylated N-glycans and "N,N-diacetyllactosamine" type N-glycans. These N-glycan changes were verified by examining gene transcript levels of the enzymes specific for their synthesis (MGAT3, ST6GAL1, and B4GALNT3) using qRT-PCR. We further evaluated the potential epigenetic influence on MGAT3 expression by treating the cell lines with 5-azacytidine, a DNA methylation inhibitor. For the first time, we provide evidence that MGAT3 expression may be epigenetically regulated by DNA hypomethylation, leading to the synthesis of the unique "bisecting GlcNAc" type N-glycans on the membrane proteins of ovarian cancer cells. Linking the observation of specific N-glycan substructures and their complex association with epigenetic programming of their associated synthetic enzymes in ovarian cancer could potentially be used for the development of novel anti-glycan drug targets and clinical diagnostic tools. Molecular & Cellular

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Abrogation of negative feedback control represents a fundamental requirement for aberrantly activated signaling pathways to promote malignant transformation and resistance to therapy. Here we identify URI, which encodes a mitochondrial inhibitor of PP1γ and PP1γ-mediated feedback inhibition of S6K1-BAD survival signaling, as an oncogene amplified and overexpressed in ovarian cancer cell lines and human ovarian carcinomas. URI is an "addicting" oncogene selectively required for the survival of ovarian cancer cells with increased URI copy number. By constitutively detaining PP1γ in inactive complexes, URI sustains S6K1 survival signaling under growth factor-limiting conditions and mediates resistance of cells to cisplatin. Thus, oncogenic activation of URI defines an important mechanism for activating mitochondrial S6K1-BAD signaling and promoting cell survival through disabling PP1γ-dependent negative feedback inhibition.

Epithelial Ovarian cancer has the highest mortality rate among gynaecological cancers. Altered glycosylation is associated with oncogenic transformation producing tumor-associated carbohydrate antigens. We investigated the potential of natural occurring anti-glycan antibodies in the diagnosis of ovarian cancer by using printed glycan array. Anti-glycan antibodies bound to 203 chemically synthesized printed glycans were detected via biotin-streptavidin fluorescence system in serum of women with normal operative findings (healthy controls; n=24) and non-mucinous borderline or ovarian cancer of various FIGO stages (n=33). Data were validated measuring blood group associated di-, tri and tetra- saccharide antigens on known ABO blood groups. Anti-glycan antibodies demonstrated high reproducibility (rc>0.9). Cluster analysis identified repetitive patterns of specific core carbohydrate structures: 11 N-linked glycans, 3 O-linked glycans, 2 glycosphingolipids. Biomarker detection revealed 24 glycans including P1 (Galα1-4Galβ1-4GlcNAcβ; p<0.001) significantly discriminating between (low-) malignant tumors and healthy controls. Comparable sensitivity and specificity with tumor marker CA125 was achieved by a panel of multivariate selected and linear combined anti-glycan antibody signals (79.2% and 84.8%, respectively). Our findings demonstrate the potential of glycan arrays in the development of a new generation of biomarkers for ovarian cancer.

We describe a relatively simple, detergent-free, enzymatic release of glycans from PVDF-immobilized GSLs, followed by the detailed structural analysis afforded by PGC-LC-ESI-MS/MS, to offer a versatile method for the analysis of tumour and cell-derived GSL-glycans. The method uses the potential of MS(2) fragmentation in negative ion ESI mode to characterize, in detail, the biologically relevant glycan structures derived from GSLs.

MELK inhibition by OTSSP167 may thus present a strategy to treat patients with aggressive, progressive, and recurrent ovarian cancer.